The reflective monumental work by Anish Kapoor was tagged with silver spray paint in the early morning hours.

According to Chicago police, seven adults were arrested on suspicion of defacing Cloud Gate, the massive Anish Kapoor public artwork in the city’s Millennium Park popularly known as “The Bean” in the early morning hours of July 2nd. Authorities have not released names of those detained at this time, but the silver spray paint used to tag it with handles such as “35th Crew” was clearly visible on the 2006 piece’s lower curves this morning.

Another pubic work, The Cancer Survivor Wall, in nearby Maggie Daley Park was also defaced as were surrounding benches.

Made up of 168 highly polished stainless steel panels, “The Bean” has become a popular and often photographed tourist attraction in Chicago’s Millennium Park since its unveiling 13 years ago. Yet this is not the first time “The Bean” has suffered vandalism. In 2009, an unknown individual scratched graffiti onto its side.

Somewhat ironically, the very construction of Could Gate was engineered to remove any trace of human effort or imprint, making the appearance of graffiti tags—essentially signatures—a direct and interesting riposte to Kapoor’s artistic intention. Indeed, the very action of scrawling one’s name on Cloud Gate could, in the right circumstances, could be an interesting comment on the anonymity (and perhaps inhumanity) of such public works themselves—this despite the fact that Kapoor’s design reflects an image of the viewer back at them.

While it’s unclear at this time whether those who defaced the work had such notions in mind, it is clear that the gleaming 220,000-pound work offers quite the blank canvas for those with paint or etching tools and will continue to do so for years to come. It’s not the first of Kapoor’s mirrored works to be defaced either: Dark Corner at the Palace of Versailles, which earned the moniker the “queen’s vagina”, received such treatment in 2015.